Infection is the most common cause of coughing up blood, accounting for about 70% of the causes of coughing up blood. The bronchial tubes are distorted and deformed by the bronchial dilation triggered by various factors such as inflammation or severe coughing, and the corresponding small arteries next to them are also deformed and then ruptured, resulting in hemoptysis and vomiting of blood.
About 20% of coughing hemoptysis is due to primary lung tumors, and coughing hemoptysis occurs when the superficial mucosa of the trachea is involved or eroded due to tumor compression or when the tumor growth site is rich in blood vessels and the vessels rupture.
In addition, coughing and vomiting of blood may occur first when the airway is traumatized or when coagulation is dysfunctional; in elderly patients, coughing and vomiting of pink foamy sputum may occur in acute heart failure; and in some women, coughing and vomiting of blood may occur during menstruation due to endometriosis and disappear after menstruation.